In order to gain insight into the role of cyclic nucleotides during ACTH stimulated adrenal growth, adrenal levels of cyclic AMP and cyclic GMP will be measured during ACTH induced adrenal hyperplasia. To further clarify the mechanism of action of ACTH, adrenal ACTH binding sites and adenylate cyclase will be solubilized employing detergents, and attempts will be made to separate the binding and enzyme activities. Finally, we will examine the role of plasma lipoproteins, HDL and LDL, in supplying substrate cholesterol for adrenal steroidogenesis. BIBLIOGRAPHIC REFERENCES: Whitley, T.W., Stowe, N.W., Ong, S., Ney, R.L., and Steiner, A. L. Control and localization of rat adrenal cyclic guanosine 3', 5'(-Monophosphate. J. Clin. Investigation 56:146,1975. Walton, J., and Ney, R.L. Current concepts of corticosteroids-uses and abuses. Disease-A-Month, June, 1975, pp.1-35.